Electric brushes for electric motors and generators



W. O. HELWIG Jan. 16, 1962 ECTRIC BRUSHES FOR ELECTRIC MOTORS AND GENERATORS United States Patent 3,017,529 ELECTRIC BRUSHES FOR ELECTRIC MOTORS AND GENERATORS Walter 0. Helwig, 2632 N. 81st St., Wauwatosa 13, Wis. Filed June 9, 1960, Ser. No. 35,040 3 Claims. (Cl. 310248) This invention relates to improvements in electric brushes and more particularly that type of electric brush shown in my prior Patent No. "2,923,842, dated February One of the objects of the invention is to improve the structure of the anti-vibration top or cap which forms a seat for the hold-down spring by projecting the antivibration spring cap beyond the front wall of the brush at the low side of the inclined top of the brush.

Another object of the present invention is to improve the anti-vibration top or cap of the multiflex type of brush structure by providing a slit in the cushion material of the anti-vibration cap, the slit extending upwardly in the cushioning material of the cap along a line following the junction of the brush parts.

Another object of the invention is to modify the top or cap of a brush to prevent its shifting, also to replace present metal tops that have been used which break off to produce a short circuit of the electric current conveyed thereto.

Another object of the invention is to provide a wider riding surface for the spring on the brush cap, thus reducing vibration and giving greatly improved commutation with less spark and more adequate bearing surface.

These and other objects of the invention will more clearly hereinafter appear by reference to the accompanying drawings forming a part of the instant specification and wherein like characters of reference designate corresponding parts throughout the several views, in which:

FIG. 1 is a. perspective view showing a solid brush structure;

FIG. 2 is a fragmentary view similar to FIG. 1 showing the cap removed;

FIG. 3 is a section on line 3-3 of FIG. 1;

FIG. 4 is a section on line 4-4 of FIG. 1;

FIG, 5 shows a perspective view of a brush with a modified cap structure;

FIG. 6 is a fragmentary perspective showing the brush structure of FIG. 5 with the cap removed;

FIG. 7 is a section on line 77 of FIG. 5;

FIG. 8 is a section on line 8-8 of FIG. 5;

FIG. 9 is a perspective view of a multiplex brush showing the modified slit top;

FIG. 10 is a fragmentary perspective view showing the top separated from the brush of FIG. 9;

FIG. 11 is a fragmentary section on line 11-11 of FIG. 9; and

FIG. 12 is a fragmentary section on line 12-12 of FIG. 9.

Referring to the form of the invention shown in FIGS. 1 through 4, the brush structure is of elongated form having side walls 1 and 2., vertical front wall 3 and rear parallel wall 4. The top 5 of the brush is inclined from the horizontal and is formed medially with a dovetailed slot 6 for receiving the top cap 7. The top cap 7 is of laminated form, the lower lamination 8 being made of neoprene or other suitable rubber composition having a proper hardness, as for instance approximating 40 on the durometer scale, while the top lamination 9 of the cap should have a hardness of approximately 115 on the durometer scale and Will be of a suitable material to prevent breakage in operation and to prevent damage to the assembly from external forces. The top lamination 9 is also of suitable hardness for association with a conventional hold-down spring, not shown, and for this purpose the upper lamination 9 must be appropriate to resist wear from contact with a hold-down spring.

The bottom lamination 8 is formed with outwardly diverging side walls for fitting within the side walls of the transverse dovetail slot 6 and the dimensions of the top cap 7 are such that the seating of the bottom lamination 8 will cause a binding between the sidewalls of the dovetail slot to secure the parts together. Appropriate lead wires 10 and 11 are provided for the brush.

It will be noted that the length of the top cap 7 is such as to project substantially beyond the front wall 3 of the brush when the parts are assembled. The opposite end of the top cap 7 terminates approximately flush with the rear face of the brush, as shown in FIG. 4.

In FIGS. 5 through 8, the brush structure illustrated is of generally greater width than the brush of FIGS. 1 through 4 as will be obvious from an inspection of FIG. 5. In this disclosure, the brush structure includes the side walls 1 and 2 front wall 3 and rear wall 4 The top of the brush, being of relatively greater width, is provided at its top angular face 5 with a relatively wide dovetailed transversely extending recess 6 best shown in FIG. 6. The recess 6 is to receive the cap 7 the latter being of laminated form as in the earlier described form of the invention, to include a bottom lamination 8 formed of neoprene or other suitable rubber composition and a hardened top lamination 9 to provide a shockresistant surface suitable to resist external forces and to properly support and be associated with a conventional hold-down spring.

The top cap 7 shown detached in FIG. 6, is shown in position in FIG. 5 and in this position it will be noted that this top cap has a reduced area '7 which projects beyond the front wall 3*. The reduced area is defined by the inner offset shoulders 14 and the projecting part provides a wider riding surface for improved com-mutation, reducing vibration and resulting in less spark. The enlarged projecting surface also provides for the accommodation and more adequate bearing surface for a larger spring.

In FIGS. 9 through 12 there is disclosed a rnultiflex brush structure comprising the sections 15- and 16. These sections are of generally rectangular form and are of such dimensions that their sides, bottoms and top edges are flush as shown. The brush sections 15 and 16 are connected at their tops by the cap, generally indicated at 17, the cap 17 including the bottom neoprene or rubber base 18 and a harder upper lamination 19, the latter being suitable for engagement with a spring and being of such form as to resist wear and to give strength against external forces. The bottom lamination 18 is formed with a transverse slit 20 which extends partially through the bottom lamination along the line of demarcation formed by the junction of the brush sections 15 and 16 at the top thereof, it being noted that the brush sections have their inner faces abutting and in flush contact. By this structure the two brush sections are connected together by a generally resilient hinge formation, the hinge formation including a hardened riding surface for an associated hold-down spring. In this structure shown in FIGS. 9 through 12, the cap, because of its structure and its composition, provides maximum flexibility and resiliency between the sections of the brush, thus producing better contact for the operating surface thereof. It is important that a maximum contact be provided between the brush and the commutator and by the resilient hinge shown between the sections there is provision for the brush sections each maintaining this maximum contact.

The brush structure of FIGS. 9 through 12 is not wedged into a dovetailed slot as in the other forms of the present invention, but seats upon the abutting flush upper ends of the brush and extends thereacross. It will also be noted that the top cap forming the hinge for the two brush sections and the riding surface for the hold-down spring occupies a greater part of the upper ends of the brush, thereby providing a maximum space for engagement with the hold-down spring and maximum riding surface therefor.

What I claim is:

1. In an electrical contact brush, a brush body formed of a pair of sections, said sections being arranged in abutting relation, and a cap structure at the top of said brush body, said cap structure being formed of a pair of adhesively connected upper and lower laminations, the lower lamination being in fixed association with the brush sections and being partially severed along a line defined by the abutting surfaces of the brush body, and the upper lamination having a relatively hard upper wear surface and being attached to the lower lamination throughout a major portion of its contact area.

2. In an electrical contact brush, a brush body having a contact surface at one end, the opposite end of said brush being inclined and formed with a transversely extending dovetailed slot, a unitary cap structure at the upper end of said brush body, said cap structure being of greater length than the transverse dimension of the brush and projecting substantially beyond the side face of the brush connected to the lower side of the inclined end, said cap structure being formed of upper and lower laminations, said lower lamination having its side walls diverging for engagement with the side walls of said slot and being formed of shock absorbing yielding and resilient material, and the upper lamination of said cap including a relatively hard upper wear surface, said upper lamination being fixed to the lower lamination.

3. The structure of claim 2 characterized in that the unitary cap structure is relatively wide throughout the area overlying the brush body and is provided with a re stricted portion which extends away from the brush body.

Great Britain Apr. 2, 1917 France Mar. 5, 1921 

